The Billionaire's Secret Bump - Chapter 20: Trapped inbetween

What was originally an ordinary day, suddenly became a historical turning point. Enormous, mysterious Cubes appeared all over the world without warning and as if Judgement Day’s spears, inserted themselves into the blue planet.

From inside the enormous Cubes, endless streams of monsters gushed out alike raging tides, utterly defeating the unguarded armies of each state in the blink of an eye.

In order for humanity to preserve its final embers, the heads of states issued orders of retreat, to no longer attack the Cubes but rather to cling to remote cities, which they turned into self-sufficient survivor bases and around which they built 100-meter-tall Walls of Life!

Many years later, while bearing the heavy weight of history, the first expeditionary force brought back a world changing piece of information. The Cubes possessed exceedingly high intelligence and they regularly transmitted mission instructions to humans nearby. The mission rewards were incredible.

Since then, humans rushed out of the confines of the walls and once more set foot on the wasteland!

- Description from Novelupdates

Set on a giant, almost finished bridge between Sadogashima and Niigata. Abandoned by the government, the bridge, and the giant man-made floating island at the center, has become a city of criminals and societal drop-outs.

Set in the same world as Durarara, but 15-20 years later. There is almost no overlap between Etsusa Bridge and the other novels.

Derek Carter never asked for a System, an apocalypse, or the pressure of being humanity’s so-called “last hope.”He was just trying to survive the daily struggles of being an orphan in Paleview City—dodging bullies, scraping together meals, and lying his way into school. Life was already hard enough.Then, one day, a blue screen pops into his vision:[Warning: The world is doomed. Try not to die.]Yeah, great. Just what he needed—cryptic doomsday messages and no instruction manual.Now, monsters are creeping into the city, reality is unraveling, and Damien’s “legendary” starting stats are barely above zero. The System promises him power, but there's just one tiny problem—he’s never won a fight in his life.Armed with sarcasm, questionable decision-making skills, and the sheer refusal to die, Damien is about to embark on the worst (and possibly last) adventure of his life. Because if the world really is ending… he’s at least going to make it someone else’s problem first.After all, heroes are overrated—survivors get to tell the story.

After the nuclear warfare, massacres started to spread throughout the entire world. The order between humans completely collapses, and the strong eats while the weak gets eaten becomes the #1 rule.